MC13202 Technical Data, Rev. 1.4

Freescale Semiconductor

23

Figure 12. RF Interface Pins

9.1.1

Single Port Operation

The integrated RF switch allows users to operate in a single port configuration. In Single Port Mode, an

internal RX switch and separate PA are used and pins RFIN_P (PAO_P) and RFIN_M (PAO_M) become

bidirectional and connect both for TX and RX. When receiving, the RX switch is enabled to the internal

LNA and the TX PA is disabled. When transmitting, the RX switch is disabled (isolating the LNA) and a

TX PA is enabled. The optional CT_Bias pin provides a reference or bias voltage which is at VDDA for

transmit and is at ground for receive. This signal can be used to provide the proper bias voltage to a balun

that converts a single-ended antenna to the differential interface required by the transceiver.

Figure 13 shows a single port example with a balun.

Figure 13. Single Port RF Operation with a Balun

The CT_Bias is connected to the balun center-tap providing the proper DC bias voltage to the balun

depending on RX or TX.

RX

SW ITCH

PA1 ENABLE

CT_Bias CONTROL

PA1

PA2

FROM TX PSM

RX ENABLE

LNA

RX

SIGNAL

RFIN_P (PAO_P)

RFIN_M (PAO_M )

CT_Bias

PAO_P

PAO_M

2

1

3

5

6

PA2 ENABLE

CT_Bias Generator

Balun

Bypass

RFIN_P (PAO_P)

RFIN_M (PAO_M)

CT_Bias

PAO_P

PAO_M

MC13202/03

L1